When Caterpillars Move In, the Yellow-Billed Cuckoo Feasts

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A yellow-billed cuckoo.CreditJohann Schumacher

By Dave Taft

May 13, 2016

Any self-respecting yellow-billed cuckoo would like its prospects this year. The sticky, webby bivouacs of Eastern tent caterpillars festoon virtually every black cherry tree in sight, and the caterpillars have chewed the poor plants virtually leafless. Caterpillars are a mainstay of the yellow-billed’s diet.

Opinions vary about what constitutes a “good” year for caterpillars. Many would say that a good year is a one without them. But if there is a silver lining to their onslaught, it is the greatly improved potential for seeing caterpillar-eating specialist birds like cuckoos.

Secretive and often difficult to observe, the yellow-billed, in appearance and behavior, contrasts sharply with the colorful, frenetic migrants swarming through the Northeast this time of year. Warblers, vireos, tanagers and gnatcatchers are tiny bundles of nerves, flitting through treetops in near perpetual motion, their gorgeous colors a blessing both for the eyes and for identification. Though you may have only a second or two to identify a warbler, if the bird is blue, orange or yellow, and is streaked, masked, spotted, barred or striped, you can eventually identify it using any number of field guides.

By contrast, the yellow-billed cuckoo (Coccyzus americanus) is long and lean, and elegantly plumed in earth tones. It hunts through spring’s budding tree limbs methodically and is often hidden behind leaves, branches, flowers and other obstacles.

When a cuckoo finds a caterpillar nest, it is undaunted by what we might consider the high “ick” factor. It sticks its head into the swarming mass to tweeze out wriggling caterpillars one at a time and, after scraping them against a branch to remove some of the irritating hairs, swallows them whole. Feeding time provides the best opportunity to watch these birds, when they can be oblivious to disturbance in the face of such abundance.

You are far more likely to hear a yellow-billed cuckoo than to see one. Though its call is instantly recognizable, it may take you a while to place it. If you grew up watching “Tarzan” or period adventure films featuring impenetrable tropical forests, the rapid-fire, rapping call of this bird, and that of Australia’s kookaburra, served as shorthand for “exotic peril,” filling pregnant silences in such films with danger and adrenaline. When the yellow-billed cuckoo calls, even familiar woodlands transform magically into deepest, darkest Africa.

The yellow-billed cuckoo and its close cousin, the black-billed cuckoo, arrive at the height of bird migration — right about now in New York City — and remain in numbers through the end of June. In my experience, they are most active in the early-morning hours, and they frequent woodland edges and clearings. To see one, or at least to hear one, plan a trip to any buggy woodland soon after sunrise in the next few weeks. Van Cortlandt Park in the Bronx and Cunningham Park in Queens are especially good places for these secretive birds, but the Ramble in Central Park and even the North Garden at Jamaica Bay Wildlife Refuge can also host cuckoos in season.